Between the eleven year span 1938 to 1949, under the marketing banner of the radio, comic book, and movie matinee serial hero Captain Midnight, there were close too, if not actually, nearly forty free Captain Midnight Radio Premium Offers. The first offers, starting in 1938 and running through 1940, were given away in conjunction with the regular weekday radio program by the Skelly Oil Company. In 1940 Ovaltine began sponsoring the program and the premiums, although Captain Midnight oriented, were more-or-less a continuation of a whole series of Little Orphan Annie premiums that preceded them.

The first of the Captain Midnight Ovaltine radio premiums was offered through the regular daily Captain Midnight script delivered over the radio Friday, November 15, 1940, and no, it wasn't a decoder. It was actually a lapel pin called The Captain Midnight American Flag Loyalty Badge. The first decoder wasn't to come until several months later.

Captain Midnight Code-O-Graphs were originally designed to be replaced one after the other on a yearly basis. The Photo-Matic version of the Code-O-Graph, pictured above, was manufactured in 1941 just prior to the outbreak of World War II for issue during the 1942 season. Because of the wartime metal shortage it was continued for use throughout the 1943 and 1944 seasons as well, making it the Code-O-Graph with the longest service life:

The 1942-1944 Photo-Matic was the second Code-O-Graph in the series. Built like a badge it had a space for a picture of the owner to be inserted, in essence making it a photo-ID badge.

The advent of World War II had an impact on the Code-O-Graph availability: the 1941 and the 1942 models were made of brass, and the attack on Pearl Harbor, which propelled the United States into World War II, caused the U.S. Government to impose restrictions on manufacturing materials. Copper and brass were considered critical materials, and most of the materials were diverted to war activities. This precluded brass being used to manufacture novelties like radio premiums.

The Photo-Matic Code-O-Graph, although not distributed until 1942, was manufactured prior to the Pearl Harbor attack. Since it, and its predecessor, were undated, the newer Code-O-Graph was used for the 1943 and 1944 seasons as well as the 1942 season, making it the Code-O-Graph with the longest service life. The cipher setting scheme was similar to the 1941 Mystery Dial model, but there was only one cipher setting window, labeled "Master Code." The word season used in context here refers to the radio broadcast season --- that is, when the Captain Midnight radio program started with and continued with all new programs for a given period of time before starting with another whole series of new programing.

The Photo-Matic Code-O-Graph, was different than other Captain Midnight decoders in that, as mentioned previously, it was designed to allow the owner to insert a photo of themself in a small open square at the top of the badge, replacing the photo of Captain Midnight that came with it. The idea for doing so was to create a personalized identification badge like those used in defense plants of the era. Once the picture of Captain Midnight was removed and the owner substituted it with a picture of their own, they were supposed to push down the four metal tabs at each of the corners so it could not be removed. As well, although NOT all Captain Midnight decoders were badges, the Photo-Matic Code-O-Graph was because it had a pin that went through a little hook on the back so it could be pinned on and worn like a badge.